ONCE the virus is originated, it is almost impossible to eradicate it. So far, in the human history, smallpox is the only infectious disease that has only been eradicated globally. It became possible through several years of global vaccination and public health interventions. In 1988, the World Health Organisation (WHO) declared to eradicate the infectious polio from the globe by 2002. But cases of polio have been recorded post-2002 as well causing hindrance to attain the desired target. COVID-19 will not be eliminated for several years until an effective vaccination with public health intervention is introduced.
The non-pharmaceutical interventions like social separation, isolations, quarantine, and lockdown definitely aid to subdue the COVID-19 outbreak among the population and delay the rise of the epidemic curve. However, such interventions cannot be the ultimate solution as the end of these measures is necessary to resume the regular business.
For the time being, there is no immediate and effective solution to the most contagious COVID-19 other than attaining herd immunity in the near future. Herd immunity is the condition when almost all the population is immune to a disease and those who are vulnerable are indirectly protected from the infection. It is achieved either by vaccination or through natural immunity. Currently, there is no vaccine against COVID-19 and 70 pharmaceutical companies are in race for developing the vaccine.
On the other hand, natural immunity can be developed after significant proportion of the people contract the disease and immunity is developed within them thus eventually protecting other non-immune or non-vaccinated people from the possible risk of infection. It is an undesired fact that COVID-19 infection will eventually spread in population until “herd immunity” is attained. However, the crucial aspect is what proportion of people should develop immunity to achieve herd immunity in a community.
There are several uncertainties associated with COVID-19. However, epidemiologists use basic reproduction number (R0), a measure of transmissibility of the virus to predict the proportion of population in a community that has immunity for developing “herd immunity” in a community. Higher value of R0 requires higher proportion of immune person in community to develop such immunity in the community. The WHO has estimated the value of R0 at 1.4 to 2.5 which provides the estimates that to obtain herd immunity within the community range, 28.5-60 per cent of the people need to develop immunity after infection of COVID-19.
Susceptibility to the infections is one of the key determinants of R0. Infection control measures and lockdown help reduce individual’s susceptibility to the infection. By effectively implementing the infection control measures and lockdown, we can even achieve the herd immunity below the threshold of 28.5-60 per cent. It is hence for the sake of achieving herd immunity, we should expect virus’s infection in population but that should be achieved at low cost of life and serious consequences of the disease.
In such case, the upmost duty of the country’s health authority is to estimate the burden of the outbreak in various age groups and demographics and bolster the public health and therapeutic counter-measures so that the possible massive outbreak will not overwhelm the health system. The epidemic might prevail for long period but once it comes within the control of the health system, its existence can be subdued to level of an endemic or a sporadic form like measles, SARS and yellow fever.
– The Rising Nepal